Projet de thèse en Sciences et génie des matériaux
Sous la direction de Jean-François Hochepied et de Thalia Chatzisymeon.
Thèses en préparation à Paris Sciences et Lettres en cotutelle avec l'Institute for Infrastructure and Environment (IIE), School of Engineering, The University of Edinburgh , dans le cadre de École doctorale Sciences des métiers de l'ingénieur (Paris) , en partenariat avec Centre des Matériaux (laboratoire) et de École nationale supérieure des mines (Paris) (établissement de préparation de la thèse) depuis le 01-10-2015 .
Self-decontaminating textiles via the in-situ synthesis of photocatalytic nanoparticles
The functionalization of textiles by photocatalytic particles has been recently studied for the purpose of conferring self-cleaning and autodecontamination properties. Direct approaches consist in impregnating suspensions of nanoparticles (by soaking, spray, layer by layer ), which leads to processing issues in term of reproducibility or scale-up. In this thesis, an alternative is developed based on in-situ synthesis of photocatalytic nanoparticles on fabrics. Our work relies principally on the thermal destabilization of zinc-ammonia complexes at moderate temperatures to form ZnO nanostructures. This method is simple and suitable with most textiles (like cotton) and can be adapted to an industrial process: solutions were prepared by dissolution of zinc precursors in ammonia solution, and then re-precipitated on the fibers through conventional heating and ammonia evaporation. The idea is to grow a dense coating of nanorods on the fibers, which is expected to be the most favorable structure to the photocatalytic efficiency (better absorption of light and adsorption of pollutant). This step of in-situ synthesis is radically different from other methods based on pre-existing particle deposition. This method of coating is expected to allow an efficient regeneration when needed. Our strategies can support a short durability because it is simple and cheap to functionalize a raw fabric (or re-functionalize a fabric after performance loss). Thereby the choice turns to ZnO, it is less expensive than TiO2 with similar photoactivity, and may be obtained in a well-crystallized state in soft conditions (near neutral pH and low temperature). In addition, ZnO is well-known to exhibit growth habit leading to rod-shaped particles, which may add other effects linked to nano-architecture and/or preferential exposed crystal faces. The main drawback of ZnO is its poor chemical stability especially in acidic conditions. The French part will focus on in-situ synthesis and characterization of nanostructures: quality of coating depending on process parameters, resistance to washing, capacity of regeneration, whereas photocatalytic efficiency tests and durability will be realized with our Scottish partner, specialized in decontamination/depollution by photocatalytic processes